Silver Coins With Patina

If by patina you mean toning, yes, there's nothing wrong with that, so long as it's attractive and regular (as opposed to unsightly and splotchy).

Toning plays little part in the grading of a coin by the TPGs - that's based on wear and detail. If the toning is particularly unsightly, it's at most a very slight detractor in determining grade.

Yep, and Wei Fun's comments still hold.

On your very attractive 2 mark, you'll notice that the patina is pretty even; the obverse may have some areas where rub or wear has caused uneven color, but this is nonetheless a very pretty example. As long as it hasn't been wiped or cleaned and then re-toned (reverse fields may betray the tell-tale hairlines, hard to say) then you can be pretty comfortable with such a specimen.

If you have a chance, there's a nifty PCGS app for smartphones, iPads etc that shows you photos of coins grade-by-grade... If you look at some of the MS65+ coins they show in their examples, you'll see some truly outstanding toning.

Also, if you look up auctions for rainbow-toned coins, you'll see that by and large they fetch a premium over similar grades that lack such color.

-SCS

The German Mark has a very nice thick patina on it, that is a good sign that no one has ever messed with the coin. It has very good eye appeal and you would expect that most 100+ year old silver coins would not be blast white.